The outcomes of hip resurfacing arthroplasty are largely dependent on prosthesis positioning. The biomechanics of notching, accurate measurement of femoral implant version and the use of computer navigation of the Birmingham Hip Resurfacing procedure were studied in this work. First, biomechanical tests were conducted with varying notch sizes and femoral positions, and it was determined that anterior notching weakens the construct (p=0.027) when the femur is in flexion and less so when in single-leg stance (p=0.155). Second, three novel techniques were used by three observers to measure the implant version in a lateral radiograph to determine which displayed a more accurate intra-class correlation. The third study examined the role of computer navigation as a learning device for improving the accuracy of femoral implant positioning using a manual alignment jig to curtail sequelae associated with malalignment.

The outcomes of hip resurfacing arthroplasty are largely dependent on prosthesis positioning. The biomechanics of notching, accurate measurement of femoral implant version and the use of computer navigation of the Birmingham Hip Resurfacing procedure were studied in this work. First, biomechanical tests were conducted with varying notch sizes and femoral positions, and it was determined that anterior notching weakens the construct (p=0.027) when the femur is in flexion and less so when in single-leg stance (p=0.155). Second, three novel techniques were used by three observers to measure the implant version in a lateral radiograph to determine which displayed a more accurate intra-class correlation. The third study examined the role of computer navigation as a learning device for improving the accuracy of femoral implant positioning using a manual alignment jig to curtail sequelae associated with malalignment.

Metal-on-metal hip resurfacing arthroplasty (MoMHRA) has undergone a recent resurgence as an alternative treatment option for young and active patients with significant hip osteoarthritis. Despite the satisfactory short-term implant survivorship, abnormal periprosthetic soft-tissue masses relating to the hip joint (pseudotumours) are being increasingly reported. These were found to be locally destructive, requiring revision surgery in a high proportion (75%) of patients, the outcome of which is poor. However, there is currently no definitive evidence of potential mechanisms involved in the occurrence of such destructive soft tissue masses. The broad aims of this thesis were: 1) to determine the extent of this emerging clinical complication (pseudotumour) with a high revision burden; and 2) to determine whether pseudotumour results from a local biological reaction to an increased wear debris burden generated by excessive MoMHRA implant wear. A clinical study investigated the prevalence of, and association between, pseudotumours and serum metal ion levels in 158 MoMHRA patients (201 hips). The overall prevalence of pseudotumour was found to be 4%, considerably higher than previously reported. The study also established that pseudotumour only occurred with elevated metal ion levels, suggesting the underlying cause is increased wear. It was postulated that pseudotumours are likely to be a biological reaction to the large amount of metal debris generated in vivo due to excessive wear. Two potential biological reactions mediating the occurrence of pseudotumours were then investigated. An in vitro clinical study demonstrated that systemic hypersensitivity type IV reaction, mediated by lymphocyte reactivity to these metals, is not the dominant biological response involved in pseudotumours. A further in vitro experiment demonstrated that metal particle-induced cytotoxicity is likely to be an important factor leading to pseudotumours. Subsequent research focused, firstly, on assessing the magnitude of bearing surface wear that occurs in pseudotumour patients, and secondly on elucidating the potential wear mechanism responsible for the increased implant wear in these patients. A retrieval study demonstrated that MoMHRA implants revised due to pseudotumour were associated with significantly greater linear wear rates. This combined with the metal ion data confirmed that pseudotumour is associated with increased wear at the MoM articulation. An edge-loading wear pattern was always found in the pseudotumour group. An in vivo study was then developed to investigate whether the edge-loading occurs during functional activities. Edge-loading in the pseudotumour group was found to occur with up to 4-fold increase in duration and up to 7-fold increase in force. This in vivo finding supported the in vitro retrieval study finding of an edge-loading wear pattern in the pseudotumour group, suggesting that edge-loading during functional activities is an important in vivo mechanism responsible for localised high wear and subsequent elevation of metal ion levels in MoMHRA patients with pseudotumours. It is concluded that pseudotumour is likely to result from a local biological reaction to increased metal debris load, generated by excessive MoMHRA implant wear due to edge-loading. In susceptible patients, the dose-dependent cytotoxicity of wear debris leads to subsequent necrosis of periprosthetic soft tissues. Clinicians need to be aware of pseudotumours and surgeons should undertake MoMHRA with great care in the knowledge that even with satisfactory component positioning, the problem can occur. In evaluating MoMHRA patients with unexplained symptoms with normal plain radiographs, further investigation with soft-tissue imaging modalities such as ultrasound or MRI is recommended.

The third generation of hip resurfacing commenced in the U.K. in the 1990’s with the Birmingham Hip Resurfacing system and is now becoming more commonplace as an attractive alternative for young and active patients due to premature failure in total hip replacement in this patient group. However the Swedish National Hip Arthroplasty Register (2010) suggests that premature failure of resurfacing arthroplasty may be more prevalent than first expected. The aim of this study is to investigate, through Finite Element Analysis, the short, medium and long term performance of Poly Methyl Methacrylate (PMMA) bone cement of the femoral component in hip resurfacing arthroplasty. The study takes a forensic engineering approach, analysing the performance of PMMA bone cement in order to provide understanding, awareness and an insight into lifestyle options. Finite Element Analysis explores and models the effect of resting periods during daily activities, patients’ bone quality and PMMA bone cement Young’s modulus on the PMMA bone cement stresses within the femoral hip resurfacing component. Mechanical tests are used to illustrate the use of the Finite Element Analysis results. Contributing to knowledge, this study verifies the significance of high metal-on-metal friction due to resting periods, developing a dynamic FEA model to quantify the premature fatigue failure of PMMA bone cement, within the femoral component of hip resurfacing arthroplasty. A decrease in bone quality added to the effect of resting periods increase the risk of PMMA fatigue failure and PMMA-metal interface failure due to an increase of PMMA tensile and shear stresses, suggesting that patients with low bone quality should avoid hip resurfacing procedures. The use of low PMMA Young’s modulus could greatly enhance the long term success of hip resurfacing arthroplasty generally and specifically reduce the risk of interface failure and PMMA bone cement failure due to resting periods and patient bone quality. Moreover, this study shows that the consequence of PMMA fatigue failure and PMMA-metal interface failure must be included in the design, patient selection, screening process, post-operative rehabilitation and long term lifestyle attributes. This study suggests that occupational therapists and patients with hip resurfacing arthroplasty should be aware of high metal-on-metal friction situations, which could lead to early failure indicated by this research. The deleterious effect of resting periods indicated by this research could be alleviated by appropriate re-initiation of synovial lubrication by movement prior to full loading. Recommendations for further work include the compilation of a PMMA bone-cement fatigue properties database and further development of the FEA modelling technique for application upon other arthroplasty procedures.

As progressivas inovações tecnológicas, na área de projeto mecânico, contribuem para a adoção de novos procedimentos cirúrgicos relacionados à ortopedia. Este trabalho trata do projeto, desenvolvimento e fabricação de dispositivos de usinagem e instrumentais cirúrgicos para aplicação em cirurgias de recapeamento da cabeça femoral em humanos e animais, buscando aperfeiçoar tal procedimento no que diz respeito a tecnologias voltadas à modelagem óssea e furação centralizada com a cabeça femoral. Nesse contexto, a relação tempo x precisão foi muito bem explorada, de forma a auxiliar com eficiência os cirurgiões e os pacientes que necessitam dessa cirurgia reduzindo a interferência da habilidade do cirurgião no resultado final da cirurgia. A fresa multilaminar sequencial, criada para usinar a cabeça femoral conforme geometria interna da prótese de recapeamento de quadril é uma importante ferramenta para redução do tempo de cirurgia, uma vez que é necessária a troca de ferramentas durante os procedimentos cirúrgicos como mostrado nesta tese. O instrumental cirúrgico, responsável para o funcionamento correto desses dispositivos de usinagem, é um guia de furação personalizado capaz de alinhar a broca e a fresa durante a modelagem da cabeça femoral, de acordo com o ângulo do colo femoral de cada paciente. Assim, este trabalho trata da concepção, desenvolvimento e fabricação de protótipos de um dispositivo de usinagem e instrumentais cirúrgicos que promovam a usinagem centralizada seguindo o ângulo do colo femoral, redução do tempo de cirurgia e da aplicação cirúrgica com prótese de recapeamento artroplastia de recapeamento canina. Os produtos desenvolvidos nesse trabalho serão nomeados como \"fresa multilaminar sequencial\", \"máscara para furação centralizada\" e \"prótese e instrumentais cirúrgicos para cães\", para a artroplastia de recapeamento de quadril. Com os desenvolvimentos, é esperada uma redução no tempo da cirurgia, bem como um aumento na segurança, possibilitando maior sucesso nesses procedimentos em humanos, bem como trás nova tecnologia para a medicina veterinária. / Progressive technological innovations in the area of mechanical design, contribute to the adoption of new surgical procedures related to orthopedics. This work addresses the design development and manufacture of machining devices and surgical instruments to be used in resurfacing surgeries of the femoral head in humans and animals, seeking to improve this procedure in regards to a new technology related to bone structure for machining and drilling aligned with the femoral head. In this context, the relation time c accuracy was very well explored, in order to assist with efficiency surgeons and patients requiring surgery that reduces the interference on the skill of the surgeon on the surgery outcome. The simultaneous development of the multilaminar-mill, designed to machine the femoral head matching the internal geometry of the resurfacing prosthesis is an important tool for reducing the surgery time, as the tool changes during surgery as shown this thesis. The surgical instrument responsible for the proper operation of these machining devices is a customized guide drill mark capable of aligning the drill and the mill during drilling and milling of the femoral head, according to the angle of the femoral neck of each patient. This work deals with the design, development and manufacturing of a machining device prototype and surgical instruments to promote the centralized machining following the angle of the femur neck the reduction of surgery time and the innovate arthroplasty surgery in humans animals. The products developed in this work are named as \"sequential multilaminar mill\", \"drilling centering mask\" and \"prosthesis and instrumental for dogs\", for hip resurfacing arthroplasty. With the developments, it is expected to reduce the surgical time, as well increasing safety, allowing greater success in these procedures.

As progressivas inovações tecnológicas, na área de projeto mecânico, contribuem para a adoção de novos procedimentos cirúrgicos relacionados à ortopedia. Este trabalho trata do projeto, desenvolvimento e fabricação de dispositivos de usinagem e instrumentais cirúrgicos para aplicação em cirurgias de recapeamento da cabeça femoral em humanos e animais, buscando aperfeiçoar tal procedimento no que diz respeito a tecnologias voltadas à modelagem óssea e furação centralizada com a cabeça femoral. Nesse contexto, a relação tempo x precisão foi muito bem explorada, de forma a auxiliar com eficiência os cirurgiões e os pacientes que necessitam dessa cirurgia reduzindo a interferência da habilidade do cirurgião no resultado final da cirurgia. A fresa multilaminar sequencial, criada para usinar a cabeça femoral conforme geometria interna da prótese de recapeamento de quadril é uma importante ferramenta para redução do tempo de cirurgia, uma vez que é necessária a troca de ferramentas durante os procedimentos cirúrgicos como mostrado nesta tese. O instrumental cirúrgico, responsável para o funcionamento correto desses dispositivos de usinagem, é um guia de furação personalizado capaz de alinhar a broca e a fresa durante a modelagem da cabeça femoral, de acordo com o ângulo do colo femoral de cada paciente. Assim, este trabalho trata da concepção, desenvolvimento e fabricação de protótipos de um dispositivo de usinagem e instrumentais cirúrgicos que promovam a usinagem centralizada seguindo o ângulo do colo femoral, redução do tempo de cirurgia e da aplicação cirúrgica com prótese de recapeamento artroplastia de recapeamento canina. Os produtos desenvolvidos nesse trabalho serão nomeados como \"fresa multilaminar sequencial\", \"máscara para furação centralizada\" e \"prótese e instrumentais cirúrgicos para cães\", para a artroplastia de recapeamento de quadril. Com os desenvolvimentos, é esperada uma redução no tempo da cirurgia, bem como um aumento na segurança, possibilitando maior sucesso nesses procedimentos em humanos, bem como trás nova tecnologia para a medicina veterinária. / Progressive technological innovations in the area of mechanical design, contribute to the adoption of new surgical procedures related to orthopedics. This work addresses the design development and manufacture of machining devices and surgical instruments to be used in resurfacing surgeries of the femoral head in humans and animals, seeking to improve this procedure in regards to a new technology related to bone structure for machining and drilling aligned with the femoral head. In this context, the relation time c accuracy was very well explored, in order to assist with efficiency surgeons and patients requiring surgery that reduces the interference on the skill of the surgeon on the surgery outcome. The simultaneous development of the multilaminar-mill, designed to machine the femoral head matching the internal geometry of the resurfacing prosthesis is an important tool for reducing the surgery time, as the tool changes during surgery as shown this thesis. The surgical instrument responsible for the proper operation of these machining devices is a customized guide drill mark capable of aligning the drill and the mill during drilling and milling of the femoral head, according to the angle of the femoral neck of each patient. This work deals with the design, development and manufacturing of a machining device prototype and surgical instruments to promote the centralized machining following the angle of the femur neck the reduction of surgery time and the innovate arthroplasty surgery in humans animals. The products developed in this work are named as \"sequential multilaminar mill\", \"drilling centering mask\" and \"prosthesis and instrumental for dogs\", for hip resurfacing arthroplasty. With the developments, it is expected to reduce the surgical time, as well increasing safety, allowing greater success in these procedures.

Today is the surface hip repacement very often surgery becouse of new studies and improvements. For young and active people it's the best way to delay implantation of a total hip replacement. The objective of this study was to perform finite-element analyses of computational model of the partial/total surface replacement, conventional partial/total replacement and physiological hip joint. We obtained strain-stress states from these analyses. All results were compared one another and then were confronted with results of the physiological hip joint. The three-dimensional computational model consists of these components: sacral, pelvic and femoral bone, muscles, artificial socket, and surface hip replacement. We were using FEM system ANSYS. The geometrical models of bones were generated by means of computed tomography (CT) images. The FE model of bone reflects two types of the bone tissues (trabecular and cortical bone) and muscles which are important when standing on one leg. The model of the muscle corresponds to isometric contraction. The implants material and bone tissues were modelled as isotropic linear elastic material. The model was loaded by force, corresponding to load by standing on one leg.

É estudada, conceitualmente a técnica de recapeamento de quadril de cães como modelo cirúrgico. A artroplastia do quadril foi desenvolvida com a finalidade de estabelecer a mobilidade articular e também no alívio da dor de pacientes humanos. Em animais, principalmente os cães, a artroplastia total, é um procedimento cirúrgico muito utilizado na articulação coxofemoral para a correção de patologias de quadril, sejam elas degenerativas traumáticas ou inflamatórias além de aliviar a dor. A artroplastia de recapeamento de quadril em humanos tem se mostrado uma técnica muito eficiente por estar próxima da anatomia natural do quadril e tem sido aplicada em pacientes jovens e ativos. A vantagem de se realizar a técnica de recapeamento é que nesta, há uma ressecção mínima da cabeça femoral e que promove uma melhora em relação à estabilidade da articulação, entretanto essa técnica ainda não é aplicada em animais. O presente trabalho tem por objetivo estudar a técnica de recapeamento de quadril de cães de forma análoga as técnicas aplicadas em humanos e também, propor um projeto de ferramental cirúrgico específico em conjunto com o protocolo cirúrgico. A técnica conceitual de artroplastia de recapeamento de quadril de cães foi desenvolvida a partir de um fêmur canino onde foram desenvolvidos os conceitos da técnica cirúrgica e o protótipo do ferramental cirúrgico necessário para o desenvolvimento desta técnica. Inicialmente foram feitas aquisições das imagens dos objetos do trabalho (fêmur canino, ferramental cirúrgico e prótese cirúrgica) que foram convertidas em arquivos CAD; a partir destes foram gerados cópias em gesso através do processo de impressão 3D do ferramental cirúrgico desde o guia de furação até a fresa de chanframento e também da prótese cirúrgica de recapeamento. A fabricação do ferramental cirúrgico obtido pelo processo de impressão 3D possibilitou uma análise visual dos protótipos que serviram de modelos para a fabricação do ferramental cirúrgico definitivo, sendo este, confeccionado em aço. Isso permitiu sua validação em bancada de laboratório através de testes realizados em modelos de ossos de cães em resina. Conclui-se que a técnica de recapeamento de quadril de cães validada em bancada de laboratório poderá ser realizada em conjunto com o ferramental cirúrgico proposto para em um futuro muito próximo ser usado em articulações de cães portadores de displasia coxofemoral devido a sua funcionalidade e à demanda de casos clínicos para este procedimento. A técnica cirúrgica de recapeamento estudada poderá ser oferecida a população a um custo acessível por ser inovadora e promissora no contexto da ortopedia veterinária. / The study conceptually describes a surgical model for dog hip resurfacing technique. Hip arthroplasty was developed to restore joint mobility and relieve of human patients pain. In animals, especially dogs, total arthroplasty is a surgical procedure commonly used to correct traumatic, degenerative and inflammatory hip diseases and alleviate pain. The resurfacing hip arthroplasty in humans, applied in young and active patients, has shown to be an efficient technique. The advantage of using this technique is that there will be a minimal resection of the femoral head, improving the stability of the joint; however it has not been applied to animals yet. The present dissertation reports on the study of hip resurfacing technique for dogs in a similar way it is applied in humans. It also proposes a specific surgical tooling design in conjunction with the surgical protocol. The technical concept of hip resurfacing arthroplasty for dogs was developed from a canine femur from which the concepts of the surgical technique and the prototypes of the necessary surgical tools were developed. Initially, images of the objects used in the work (canine femur, surgical tools and surgical prosthesis) were acquired. They were then converted into CAD files, which generated plaster copies of surgical tools, from the hole guide to the to cutter and chamfer, and also surgical resurfacing prosthesis through the 3D printing process. The manufacture of the surgical tools models obtained by 3D printing process allowed a visual analysis of the prototypes that served as references for the definitive surgical tool made in steel. Such tools were validated by means of laboratory bench tests using resin models of dogs\' bones. It was possible to conclude that the technique of hip resurfacing in dogs can be employed in conjunction with the proposed surgical tools in the joints of dogs with hip dysplasia in a very near future. Due to its full functionality and large demand of clinical cases for this procedure, the technique may be offered to the population at an affordable cost. It is also an innovative and promising technique in the context of veterinary orthopedics.

É estudada, conceitualmente a técnica de recapeamento de quadril de cães como modelo cirúrgico. A artroplastia do quadril foi desenvolvida com a finalidade de estabelecer a mobilidade articular e também no alívio da dor de pacientes humanos. Em animais, principalmente os cães, a artroplastia total, é um procedimento cirúrgico muito utilizado na articulação coxofemoral para a correção de patologias de quadril, sejam elas degenerativas traumáticas ou inflamatórias além de aliviar a dor. A artroplastia de recapeamento de quadril em humanos tem se mostrado uma técnica muito eficiente por estar próxima da anatomia natural do quadril e tem sido aplicada em pacientes jovens e ativos. A vantagem de se realizar a técnica de recapeamento é que nesta, há uma ressecção mínima da cabeça femoral e que promove uma melhora em relação à estabilidade da articulação, entretanto essa técnica ainda não é aplicada em animais. O presente trabalho tem por objetivo estudar a técnica de recapeamento de quadril de cães de forma análoga as técnicas aplicadas em humanos e também, propor um projeto de ferramental cirúrgico específico em conjunto com o protocolo cirúrgico. A técnica conceitual de artroplastia de recapeamento de quadril de cães foi desenvolvida a partir de um fêmur canino onde foram desenvolvidos os conceitos da técnica cirúrgica e o protótipo do ferramental cirúrgico necessário para o desenvolvimento desta técnica. Inicialmente foram feitas aquisições das imagens dos objetos do trabalho (fêmur canino, ferramental cirúrgico e prótese cirúrgica) que foram convertidas em arquivos CAD; a partir destes foram gerados cópias em gesso através do processo de impressão 3D do ferramental cirúrgico desde o guia de furação até a fresa de chanframento e também da prótese cirúrgica de recapeamento. A fabricação do ferramental cirúrgico obtido pelo processo de impressão 3D possibilitou uma análise visual dos protótipos que serviram de modelos para a fabricação do ferramental cirúrgico definitivo, sendo este, confeccionado em aço. Isso permitiu sua validação em bancada de laboratório através de testes realizados em modelos de ossos de cães em resina. Conclui-se que a técnica de recapeamento de quadril de cães validada em bancada de laboratório poderá ser realizada em conjunto com o ferramental cirúrgico proposto para em um futuro muito próximo ser usado em articulações de cães portadores de displasia coxofemoral devido a sua funcionalidade e à demanda de casos clínicos para este procedimento. A técnica cirúrgica de recapeamento estudada poderá ser oferecida a população a um custo acessível por ser inovadora e promissora no contexto da ortopedia veterinária. / The study conceptually describes a surgical model for dog hip resurfacing technique. Hip arthroplasty was developed to restore joint mobility and relieve of human patients pain. In animals, especially dogs, total arthroplasty is a surgical procedure commonly used to correct traumatic, degenerative and inflammatory hip diseases and alleviate pain. The resurfacing hip arthroplasty in humans, applied in young and active patients, has shown to be an efficient technique. The advantage of using this technique is that there will be a minimal resection of the femoral head, improving the stability of the joint; however it has not been applied to animals yet. The present dissertation reports on the study of hip resurfacing technique for dogs in a similar way it is applied in humans. It also proposes a specific surgical tooling design in conjunction with the surgical protocol. The technical concept of hip resurfacing arthroplasty for dogs was developed from a canine femur from which the concepts of the surgical technique and the prototypes of the necessary surgical tools were developed. Initially, images of the objects used in the work (canine femur, surgical tools and surgical prosthesis) were acquired. They were then converted into CAD files, which generated plaster copies of surgical tools, from the hole guide to the to cutter and chamfer, and also surgical resurfacing prosthesis through the 3D printing process. The manufacture of the surgical tools models obtained by 3D printing process allowed a visual analysis of the prototypes that served as references for the definitive surgical tool made in steel. Such tools were validated by means of laboratory bench tests using resin models of dogs\' bones. It was possible to conclude that the technique of hip resurfacing in dogs can be employed in conjunction with the proposed surgical tools in the joints of dogs with hip dysplasia in a very near future. Due to its full functionality and large demand of clinical cases for this procedure, the technique may be offered to the population at an affordable cost. It is also an innovative and promising technique in the context of veterinary orthopedics.

Hip resurfacing arthroplasty has changed the treatment of end stage arthritis without severe deformity for young, active adults. Presently, there are varying clinical approaches to implant design selection and cementation techniques. The purpose of this project is to determine what amount of reamer-femoral component offset allows for the best cement penetration into the femoral head. Rapid prototyped femoral component models were produced with reamer femoral component offsets of 0.0 mm, 0.5 mm, and 1.0 mm. After implantation onto models of reamed femoral heads made from high-density open-cell reticulated carbon foam, cement penetration was assessed from cross-sections of the foam-implant unit. Increased offset was found to decrease the extent of cement over penetration from the dome and chamfer. Increased offset also yielded optimal cement penetration as measured from the walls. Finally, increased offset was found to increase the height of cement mantle formation while maintaining complete seating of all implants.